The Importance of Seeing Impermanence

We pay attention to the sense fears and all the conditioning that arises from internally and externally in both. It takes a somewhat more refined attention to see the arising and passing away or the impermanence of the sense base. The reason I think the Buddha emphasized this aspect of seeing the arising, the passing away so often why he emphasized it in the refrain is because the insight into impermanence is the doorway of seeing and understanding the other characteristics.